The solitary pulmonary nodule-deciding when to act?

Solitary pulmonary nodules (SPNs) are commonly encountered in pulmonary practice. Their management is complex, and multiple clinical factors must be considered. The three common management strategies applied to solitary pulmonary nodules are careful observation, diagnostic testing, and surgery. Fundamental concepts derived from decision analysis can be used to help clinicians choose optimal management strategies for individual patients with SPNs. This process begins with estimating the pretest probability of cancer. Then the consequences of treatment are considered-including the benefit of surgery if the patient has cancer and the harm of treatment if the patient does not have cancer. Patient comorbidities and competing risks affect the consequences of treatment. Knowledge of the benefits and harms of treatment allows clinicians to determine the treatment threshold and then rationally develop the optimal management plan. Probability revision using the pretest probability, test characteristics, and Bayes theorem is used to refine the probability of cancer until a decision threshold is reached and definitive treatment can be determined. Patients with very low pretest probability of cancer are managed with a strategy of careful observation by serial computed tomography (CT). Patients who have a high pretest probability of cancer merit surgical diagnosis. Patients with an intermediate pretest probability of cancer go on to further diagnostic testing, primarily with CT-guided fine needle aspiration or positron-emission tomography. Patient preferences are considered throughout the process because the absolute difference in outcome between some strategies may be small.